Bone marrow samples from patients with acute nonlymphocytic leukemia will be obtained at intervals prior to and during early therapy with the three-drug combination consisting of cytosine arabinoside, daunorubicin, and 6-thioguanine. Samples will be stained with a fluorescent dye and analyzed for DNA content by flow cytometry. The principal objectives of these studies will be to determine whether synchronization and/or recruitment occurs, and also investigate whether the metachromatic fluorochrome acridine orange can be used to distinguish subpopulations by multiparameter analysis. Additional patients with other leukemias and lymphomas will be monitored by flow cytometry, especially those with high growth fractions. In these studies we will attempt to determine whether any observed drug-induced perturbations in cell cycle progression can be exploited therapeutically. For patients in relapse or resistant to standard therapy, experimental drugs or drug combinations will be tested, including acridinyl anisidide (AMSA), high dose thymidine, and others. Cell cultures will also be used to explore the possible kinetic basis for any observed cytotoxic and/or synergistic effects of the drugs employed in patient treatment. In addition, they will be used to test new or revised fluorescent staining methods used in flow cytometry. We will also continue to modify our program for DNA histogram analysis, with the objective of making it more nearly automatic and less dependent on interaction with the user.